1. Field of the Invention
The present invention relates to an organic electroluminescent display device, and more particularly, to an organic electroluminescent display device in which charge damage occurring at wiring near the periphery is prevented or reduced, and wiring is facilitated during manufacturing by controlling an angle of an edge part of the wiring near the periphery.
2. Description of Related Art
Display devices using light emitting elements including organic electroluminescent (EL) device have actively been developed lately. The organic EL device is suitable for a display device having a thin profile and enhanced viewing angles since backlight required in liquid crystal display devices is not required as the organic EL device is a self-emitting display device.
A type of organic EL device has a structure in which an organic thin film layer is formed between the anode that is a transparent electrode such as ITO and the cathode fabricated using a metal having low work function such as Ca, Li and Al. When a forward voltage is applied to the organic EL device, holes and electrons are respectively injected from the anode and the cathode, the injected holes and electrons are combined to form excitons, and the excitons are emitted and recombined to cause electroluminescence.
An organic electroluminescent display device 100 using the above-referenced organic EL device is illustrated in FIG. 1, which is a plan view for showing a conventional organic electroluminescent display device.
The organic electroluminescent device 100 includes an upper power supply voltage line 110, a lower power supply voltage line 120, a cathode voltage line 130, a scan driver 140, a data driver 150, an active power supply voltage line 160 and a pixel region 170.
As illustrated in FIG. 1, the organic electroluminescent display device 100 includes the pixel region 170 on which unit pixels emitted in certain colors are arranged at a central part. The upper and lower power supply voltage lines 110, 120 supply a power supply voltage from upper and lower sides, respectively, of the pixel region 170. The scan driver 140 applies a selection signal to one side of the pixel region 170, and the cathode voltage line 130 transmits a cathode voltage to the other side of the pixel region 170. The data driver 150 applies a data signal to the pixel region 170 from a location below the lower power supply voltage line 120.
In the organic electroluminescent display device 100, a power supply voltage is applied to the pixel region 170 through the active power supply voltage line 160 from the upper power supply voltage line 110 and the lower power supply voltage line 120. Further, a cathode voltage is applied to the pixel region 170 from the cathode voltage line 130. When a selection signal and a data signal are applied from the scan driver 140 and the data driver 150, respectively, driving circuits formed at unit pixels are switched on so that a certain image is displayed on the pixel region 170 by applying currents corresponding to the power supply voltage and the data signal to organic EL devices (not illustrated in FIG. 1) formed at the pixel region 170.
The organic electroluminescent display device 100 is wired with a plurality of power supply lines and signal lines so that a certain power supply is supplied to the scan driver 140 and the data driver 150 to drive the organic EL devices. A part A of FIG. 1 is described below as one example of wiring and arrangement near the periphery of a conventional organic electroluminescent display device.
FIG. 2 is an expanded plan view of the part A of FIG. 1.
As seen in FIG. 2, a signal line 141, a scan driver power supply voltage line 142 and a scan driver cathode voltage line 143 are formed near the upper power supply voltage line 110. The scan driver cathode voltage line 143 may also be referred to as a ground voltage line or a grounding voltage line.
The upper power supply voltage line 110 is bent at a perpendicular angle, and has edge parts located at corners where the horizontal portion of the upper power supply voltage line 110 is connected to the vertical portions of the upper power supply voltage line 110. The signal line 141 is arranged along the upper power supply voltage line 110 and is similarly bent at a perpendicular angle. Further, the power supply voltage line 142 and the scan driver cathode voltage line 143 for transmitting a power supply voltage to the scan driver 140 are formed at an inner side of the signal line 141. It can be seen in FIG. 2 that the power supply voltage line 142 and the scan driver cathode voltage line 143 are parallel to each other and run adjacently to each other along the vertical portion of the power supply voltage line 142.
In a conventional organic electroluminescent display device, a power supply voltage line is wired near the periphery and has a width wider than other wirings in consideration of the voltage drop. However, since respective edge parts of conventional power supply voltage line and other wirings are perpendicularly wired in the same direction, the length of the conventional power supply voltage line and other wirings is increased, and charges are accumulated on edge parts during manufacturing process due to charge characteristics. In other words, the smaller the angle of the edge parts and the sharper edges are, the easier charges are accumulated on the edge parts. Therefore, the conventional organic electroluminescent display device suffers from a disorder occurred by charge damage to inner wirings and metal patterns since charges are distributed between adjacent wirings having the edge parts bent in the same direction according to the degree of accumulation of the charges. In addition, wirings are not easily arranged in the conventional organic electroluminescent display device because the edge parts are perpendicularly constructed so that space efficiency is reduced.